Expose change reason to admin form

Fixes #853

AUTHORS.rst

@@ -90,6 +90,7 @@ Authors
 - Lucas Wiman
 - Maciej "RooTer" Urbański
 - Marcelo Canina (`marcanuy <https://github.com/marcanuy>`_)
+- Marco Sirabella
 - Mark Davidoff
 - Martin Bachwerk
 - Marty Alchin

CHANGES.rst

@@ -24,6 +24,7 @@ Unreleased
   ``HistoricalRecords.context.request``) under some circumstances (gh-1188)
 - Made ``HistoryRequestMiddleware`` async-capable (gh-1209)
 - Fixed error when setting ``table_name`` with ``inherit=True`` (gh-1195)
+- Allow setting change reason on admin panel modifications (gh-??)
 
 3.3.0 (2023-03-08)
 ------------------

simple_history/admin.py

@@ -1,11 +1,12 @@
-from django import http
+from django import forms, http
 from django.apps import apps as django_apps
 from django.conf import settings
 from django.contrib import admin
 from django.contrib.admin import helpers
 from django.contrib.admin.utils import unquote
 from django.contrib.auth import get_permission_codename, get_user_model
 from django.core.exceptions import PermissionDenied
+from django.forms import fields
 from django.shortcuts import get_object_or_404, render
 from django.urls import re_path, reverse
 from django.utils.encoding import force_str
@@ -224,9 +225,31 @@ def render_history_view(self, request, template, context, **kwargs):
 
     def save_model(self, request, obj, form, change):
         """Set special model attribute to user for reference after save"""
+        obj._change_reason = form.cleaned_data["change_reason"]
         obj._history_user = request.user
         super().save_model(request, obj, form, change)
 
+    class form(forms.ModelForm):
+        change_reason = forms.CharField(required=False)
+
+    def get_fields(self, request, obj=None):
+        return [
+            field
+            for field in super().get_fields(request, obj)
+            if field != "change_reason"
+        ]
+
+    def get_fieldsets(self, request, obj=None):
+        return super().get_fieldsets(request, obj) + [
+            (
+                "History",
+                {
+                    "classes": ["collapse"],
+                    "fields": ["change_reason"],
+                },
+            )
+        ]
+
     @property
     def content_type_model_cls(self):
         """Returns the ContentType model class."""

simple_history/tests/tests/test_admin.py

@@ -218,6 +218,20 @@ def test_history_user_on_save_in_admin(self):
             [p.history_user for p in Poll.history.all()], [self.user, self.user]
         )
 
+    def test_history_change_reason_on_save_in_admin(self):
+        self.login()
+
+        change_reason = "New change reason"
+        # Ensure polls created via admin interface save correct user
+        poll_data = {
+            "question": "new poll?",
+            "pub_date_0": "2012-01-01",
+            "pub_date_1": "10:00:00",
+            "change_reason": change_reason,
+        }
+        self.client.post(reverse("admin:tests_poll_add"), data=poll_data)
+        self.assertEqual(Poll.history.get().history_change_reason, change_reason)
+
     def test_underscore_in_pk(self):
         self.login()
         book = Book(isbn="9780147_513731")